阅读说明：本技术 一种高纯度甲基丙烯醛的吸收和精制方法 (Absorption and refining method of high-purity methacrolein ) 是由 赵炯烽 王伟松 席蓝萍 王胜利 秦飞 于 2021-10-18 设计创作，主要内容包括：本发明属于精细化工领域,涉及一种高纯度甲基丙烯醛的吸收及精制的方法。本发明采用苯氧乙醇、二乙二醇单苯醚或两者的混合物作为吸收剂,吸收氧化步骤混合气体中的甲基丙烯醛,并经过静置分层、精馏得到纯度大于99％的甲基丙烯醛。该工艺吸收效率高、产品纯度高、吸收剂回收套用简单且无毒、整个工艺安全性高、操作简单、吸收剂损失少,适合工业化生产。(The invention belongs to the field of fine chemical engineering, and relates to a method for absorbing and refining high-purity methacrolein. According to the invention, phenoxyethanol, diethylene glycol monophenyl ether or a mixture of phenoxyethanol and diethylene glycol monophenyl ether are used as an absorbent to absorb methacrolein in mixed gas in the oxidation step, and the methacrolein with the purity of more than 99% is obtained through standing, layering and rectification. The process has the advantages of high absorption efficiency, high product purity, simple recycling and application of the absorbent, no toxicity, high safety of the whole process, simple operation, less loss of the absorbent and suitability for industrial production.)

1. A method for absorbing and refining high-purity methacrolein is characterized by comprising the following steps:

s1, cooling the mixed gas obtained by selective oxidation of isobutene or tertiary butanol, and then feeding the cooled mixed gas into an absorption tower;

s2, using phenoxyethanol, diethylene glycol monophenyl ether or a mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as an absorbent to perform countercurrent absorption on the mixed gas;

s3, standing and layering the absorption liquid containing methacrolein, removing the upper water phase, and feeding the heavy components into a rectifying tower;

and S4, rectifying the heavy component to obtain high-purity methacrolein, and returning the tower bottom material to the absorption tower to be used as an absorbent for recycling.

2. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: in S1, the content of methacrolein in the mixed gas obtained by selective oxidation of isobutene or tert-butanol is 4-15 v/v%, and the mixed gas is cooled to 10-20 ℃ and then enters an absorption tower.

3. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: the absorbent selected in S2 is a mixed solvent of phenoxyethanol and diethylene glycol monophenyl ether in a mass ratio of 10: 1-5: 1.

4. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: the absorption conditions in the S2 are that the temperature of the bottom of the absorption tower is 12-20 ℃, and the temperature of the absorbent is 12-25 ℃.

5. The method for absorbing and purifying high-purity methacrolein according to claim 4, wherein: the gas-liquid mass ratio in the absorption process is 1: 1.5-1: 5.

6. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: and standing and layering for 1-2 h in S3.

7. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: the rectification condition in the S4 is that the bottom temperature is 70-85 ℃.

8. The method for absorbing and purifying high-purity methacrolein according to claim 7, wherein: the operation reflux ratio is 0.5-5.

9. The method for absorbing and purifying high-purity methacrolein according to claim 1, wherein: after the absorbent is recycled for at least 5 times, impurities such as methacrylic acid and the like are removed by distillation, and the absorbent is recycled.

Technical Field

The invention belongs to the field of fine chemical engineering, and particularly relates to a method for absorbing and refining high-purity methacrolein.

Background

Methacrolein is an important chemical raw material, methacrylic acid can be obtained by further oxidation, and products such as methyl methacrylate, glycidyl methacrylate and the like are derived; methylacrolein is reduced to obtain methallyl alcohol which is an important raw material of a new generation of high-performance water reducing agent; besides, methacrolein is also useful for copolymer and resin manufacture.

At present, the method for producing the methacrolein is mainly an isobutene or tert-butyl alcohol selective oxidation method, and the method is green and environment-friendly. However, the product obtained by the method is in a gas state, which contains a large amount of diluent gas (such as nitrogen and the like), and the content of methacrolein is low, so that methacrolein needs to be separated and obtained by an absorption method.

Patent CN 1817844A adopts water as absorbent to absorb methacrolein, but because the intersolubility of water and methacrolein is poor, a large amount of water is needed for absorption, the absorption efficiency is low, and the energy consumption is high.

Patent GP2110031 adopts methanol as an absorbent to improve the absorption efficiency, but the boiling point of the methanol is too low, and the methanol is easy to vaporize in the absorption process, so that a large amount of methanol is discharged along with tail gas, the methanol loss is high, and safety accidents are easy to cause.

The patent US3957880 uses ethanol and isopropanol as absorbents, although the boiling point of these absorbents is higher than that of methanol, the existence of a large amount of diluent gas in the oxidation reaction can still lead the absorbents to be carried away, causing loss, and the mutual solubility of the two alcohols and water is good, the water in the reaction product can also be absorbed, causing separation difficulty.

Patent CN101844973A adopts alcohols with carbon number greater than 4 as absorbent, which reduces the loss of absorbent to a certain extent, but alcohols with carbon number greater basically have strong pungent smell (for example, butanol has pungent smell, which can cause cough), resulting in serious air pollution after the exhaust of the absorbed tail gas, and some alcohols have lower flash points, which is unsafe to use.

CN103833537A adopts alkanes with 6-8 carbon atoms as absorbent, but the boiling point of the alkanes is slightly different from that of methacrolein, so that the separation is difficult, and the low boiling point also causes more absorbent loss.

The patent CN101020625 adopts ionic liquid for absorption, and has high absorption efficiency, but the ionic liquid is expensive and difficult to use on a large scale.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for absorbing and refining high-purity methacrolein, which has high absorption rate of methacrolein, is convenient to separate and is harmless.

In order to solve the problems, the technical scheme adopted by the invention is as follows:

a method for absorbing and refining high-purity methacrolein is characterized by comprising the following steps:

s1, cooling the mixed gas obtained by selective oxidation of isobutene or tertiary butanol, and then feeding the cooled mixed gas into an absorption tower;

s2, using phenoxyethanol, diethylene glycol monophenyl ether or a mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as an absorbent to perform countercurrent absorption on the mixed gas;

s3, standing and layering the absorption liquid containing methacrolein, removing the upper water phase, and feeding the heavy components into a rectifying tower;

and S4, rectifying the heavy component to obtain high-purity methacrolein, and cooling the tower bottom material and returning the cooled tower bottom material to the absorption tower to be used as an absorbent for recycling.

In a preferred embodiment of the present invention, in S1, the gas obtained by selective oxidation of isobutylene or tert-butyl alcohol is cooled to 10 to 20 ℃ and then introduced into an absorption column. The gas temperature is too high, the absorption efficiency is reduced, the gas temperature is too low, and the energy consumption required for cooling is increased.

In a preferred embodiment of the present invention, the absorbent selected in S2 is a mixed solvent in which the mass ratio of phenoxyethanol to diethylene glycol monophenyl ether is 10:1 to 5: 1. The freezing point of the phenoxyethanol is higher than that of the diethylene glycol monophenyl ether, but the water solubility of the phenoxyethanol is lower than that of the diethylene glycol monophenyl ether, and the phenoxyethanol and the diethylene glycol monophenyl ether can well solve the problems of the freezing point and the water solubility when being mixed for use.

In a preferred embodiment of the present invention, the absorption conditions in S2 are such that the bottom temperature of the absorption column is 12 to 20 ℃ and the absorbent temperature is 12 to 25 ℃. The temperature of the absorbent and the bottom of the absorption tower is too high, and the absorption efficiency is reduced; the temperature is too low and the energy consumption is increased.

In a preferred embodiment of the present invention, the gas-liquid mass ratio in the absorption process in S2 is selected to be 1:1 to 1:10, more preferably 1:1.5 to 1: 5. The larger the dosage of the absorbent is, the better the absorption effect is, but the energy consumption required by the subsequent rectification process is larger; the absorbent dosage is too small, and the absorption effect can not meet the requirement.

In a preferred embodiment of the present invention, the time for the absorption liquid to stand and stratify in S3 is 1 to 2 hours. The absorption liquid is kept stand for layering, part of water can be separated from the absorption liquid, and layered water can be removed through liquid separation, so that energy consumption required by subsequent rectification is reduced, and the product purity is improved.

In a preferred embodiment of the present invention, the temperature of the bottom of the rectifying column in S4 is 70 to 85 ℃, and more preferably 75 to 78 ℃. The reflux ratio in the rectification process is 0.5-5, and the preferred reflux ratio is 0.5-1.5. Because the content of impurities in the absorption liquid is low and the difference between the boiling points of the methacrolein and the absorbent is large, a smaller reflux ratio can be selected, and the production efficiency is improved; however, the reflux ratio is too small, and the purity of the product cannot meet the requirement.

The tail gas after absorption comprises 0.1-0.3 v/v% of methacrolein, 0.15-0.25 v/v% of isobutene, 89-90 v/v% of nitrogen, 0.1-0.2 v/v% of oxygen, 0.3-0.5 v/v% of carbon monoxide and carbon dioxide, 0.01-0.08 v/v% of methacrylic acid, trace acetone and the like.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a method for absorbing and refining high-purity methacrolein, which takes a gas phase product obtained by selectively oxidizing isobutene or tertiary butanol as a raw material, and obtains the methacrolein with the purity of more than 99 percent after absorption, standing, layering and rectification. The process has the advantages of good absorption effect, simple operation, less absorbent loss, low energy consumption, high product purity and high safety of the whole process, and is suitable for industrial production.

In particular, the present invention has the following outstanding advantages over the prior art:

(1) green and safe: the absorbent used in the invention is one or a mixture of phenoxyethanol and diethylene glycol monophenyl ether, wherein phenoxyethanol is commonly used in cosmetics and has high safety level, so that the whole operation process has little harm to operators and high safety;

(2) the absorption effect is good: the phenoxyethanol and the diethylene glycol monophenyl ether are low-viscosity solvents, have good intersolubility with the methacrolein, are used for absorbing the methacrolein, and have high absorption efficiency;

(3) the absorbent loss is small, and the separation is convenient: the boiling points of phenoxyethanol and diethylene glycol phenyl ether both exceed 240 ℃, and the phenoxyethanol and the diethylene glycol phenyl ether are not easy to volatilize, so that the loss is very small at a high gas flow rate; and because the difference between the boiling point (69 ℃) of the methylacrolein and the two is very large, the rectification is convenient, the production efficiency is high, and the method is suitable for industrial production.

Detailed Description

The embodiments and effects of the present invention are further illustrated by the following specific examples.

Example 1

And cooling the gas-phase product after the oxidation of the isobutene to 15 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption is carried out by using phenoxyethanol (15 ℃) with the mass 5 times of that of the gas. The volume contents of the gases before and after absorption are shown in Table 1 (the data in the table are volume percentages).

The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column by standing for 1 hour was 6.4%. In the rectification operation, the column bottom temperature was 75 ℃ and the reflux ratio was 0.5, to obtain high-purity methacrolein product having the composition shown in Table 2 (data in the table are in% by mass).

Example 2

And cooling the gas-phase product after the oxidation of the isobutene to 15 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption was carried out using diethylene glycol monophenyl ether (15 ℃ C.) in an amount of 5 times the mass of the gas. The volume contents of the gases before and after absorption are shown in Table 3 (the data in the table are volume percentages).

The absorption liquid obtained from the bottom of the absorption tower is kept still for 2 hours for layering to obtain a heavy phase with the methacrolein content of 6.1 percent, and the heavy phase is rectified. In the rectification operation, the column bottom temperature was 80 ℃ and the reflux ratio was 1.0, to obtain high-purity methacrolein product having the composition shown in Table 4 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.43	0.14	0.06	0.20	0.18

Example 3

And cooling the gas-phase product after the oxidation of the isobutene to 15 ℃, and then feeding the gas-phase product into a filler absorption tower. The mixture of phenoxyethanol and diethylene glycol monophenyl ether with the mass 5 times of that of the gas is adopted for absorption, and the content of phenoxyethanol in the mixture is 90 percent by mass and the temperature is 15 ℃. The volume contents of the gases before and after absorption are shown in Table 5 (the data in the table are volume percentages).

The content of methacrolein in the absorption liquid obtained from the bottom of the absorption tower is 6.3%, and the heavy phase is obtained by standing for 1.5 hours for layering and rectified. In the rectification operation, the column bottom temperature was 80 ℃ and the reflux ratio was 0.5, to obtain high-purity methacrolein product having the composition shown in Table 6 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.23	0.22	0.09	0.23	0.30

Example 4

And cooling the gas-phase product after the oxidation of the isobutene to 15 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption is carried out by using phenoxyethanol (15 ℃) with the mass 2 times of that of the gas. The volume contents of the gases before and after absorption are shown in Table 7 (the data in the table are volume percentages).

The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column by standing for 1 hour was 12.2%. In the rectification operation, the column bottom temperature was 75 ℃ and the reflux ratio was 1.5, to obtain high-purity methacrolein product having the composition shown in Table 8 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.51	0.14	0.07	0.10	0.12

In this example, the amount of the absorbent used was reduced, the absorption efficiency was decreased, and the concentration of methacrolein in the absorption liquid was increased.

Example 5

And cooling the gas-phase product after the oxidation of the isobutene to 15 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption is carried out by using phenoxyethanol (15 ℃) with the mass 8 times of that of the gas. The volume contents of the gases before and after the absorption are shown in Table 9 (the data in the table are volume percentages).

The content of methacrolein in the heavy phase obtained by layering the absorption liquid obtained at the bottom of the absorption column by standing for 1.5 hours was 3.5%. In the rectification operation, the column bottom temperature was 75 ℃ and the reflux ratio was 1.0, to obtain high-purity methacrolein product having the composition shown in Table 10 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.43	0.16	0.08	0.17	0.16

In this example, the absorption efficiency was improved by adding the absorbent, and the concentration of methacrolein in the absorption liquid was decreased.

Example 6

And cooling the gas-phase product after the oxidation of the isobutene to 10 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption was carried out using diethylene glycol monophenyl ether (10 ℃ C.) in an amount of 5 times the mass of the gas. The volume contents of the gases before and after the absorption are shown in Table 11 (the data in the table are volume percent contents).

The absorption liquid obtained from the bottom of the absorption tower is kept still for 2 hours for layering to obtain a heavy phase with the methacrolein content of 6.8 percent, and the heavy phase is rectified. In the rectification operation, the column bottom temperature was 80 ℃ and the reflux ratio was 1.0, to obtain high-purity methacrolein product having the composition shown in Table 12 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.47	0.14	0.05	0.19	0.18

In this example, the absorption temperature was lowered, the absorption efficiency was improved, and the methacrolein content in the absorption liquid was increased.

Example 7

And cooling the gas-phase product after the oxidation of the isobutene to 20 ℃, and then feeding the gas-phase product into a filler absorption tower. The absorption was carried out using diethylene glycol monophenyl ether (20 ℃ C.) in an amount of 5 times the mass of the gas. The volume contents of the gases before and after the absorption are shown in Table 13 (the data in the table are volume percent contents).

The absorption liquid obtained from the bottom of the absorption tower is kept still for 2 hours for layering to obtain a heavy phase with the methacrolein content of 5.7 percent, and the heavy phase is rectified. In the rectification operation, a high-purity product methacrolein was obtained with a column bottom temperature of 80 ℃ and a reflux ratio of 1.0, and the composition thereof is shown in Table 14 (data in the table are in% by mass).

Methylacrolein	Methacrylic acid	Acetic acid	Water (W)	Others
					99.44	0.15	0.04	0.18	0.17

In this example, the temperature of the absorption liquid was increased, the absorption efficiency was decreased, and the concentration of methacrolein in the absorption liquid was decreased.

The invention adopts low-toxicity phenoxyethanol, diethylene glycol monophenyl ether or the mixture of the phenoxyethanol and the diethylene glycol monophenyl ether as the absorbent of methacrolein, and has high absorption efficiency; the two absorbents have high boiling points (the boiling point of phenoxyethanol is 247 ℃), and the loss in the absorption process is very small; the difference between the boiling point of the methyl acrolein and the boiling point of the methyl acrolein is large (the difference between the boiling point of the methyl acrolein and the boiling point of the methyl acrolein is larger than 175 ℃), the intersolubility of the methyl acrolein and the water is poor, the rectification separation is facilitated, and the method is suitable for industrial production.